Transcript Basic Electrical

ELECTRICAL
www.safetyworksmaine.com
Basic Electrical 1910. 301-305
Practical Safeguarding of employees is
broken down into:
• Design safety standards for electrical systems.
• Safety-related work practices
• Safety - related maintenance requirements.
• Safety requirements for special equipment
www.safetyworksmaine.com
Basic Electrical 1910. 301-305
Design safety standards for electrical
systems.
Standards found in 1910.302-308 are design
safety standards for electric utilization of all
electric equipment used to provide electric
power and light for employee workplaces.
www.safetyworksmaine.com
Basic Electrical 1910. 301-305
Safety - related work practices.
These regulations are contained in 1910.331.335 and require the employer to train and
equip designated employees to maintain
facility’s electrical equipment.
www.safetyworksmaine.com
Definitions applicable are found
in 1910.399
This standard is used to define common
terms used in the electric industry and
National Electrical Code (NEC). It includes
the classes of hazardous locations.
www.safetyworksmaine.com
Basic Electrical 1910. 302
Electric Utilization Systems
Scope- Covered electrical installations and
utilization equipment installed on or used
within or on buildings, structures, and other
premises including:
•Yards
•Carnivals
•Parking and other lots
•Mobil homes & recreational vehicles
•Industrial substations
•Conductors
www.safetyworksmaine.com
Basic Electrical 1910. 302
Electric utilization systems
•Does not cover-ships, watercraft, railroad
rolling stock, or automotive vehicles unless
recreational, installation underground,
installation of railways, communication
equipment, or electrical installation under the
exclusive control of electric utilities.
www.safetyworksmaine.com
General Electrical 1910. 303
Design safety standards for electrical
systems.
a) Use only approved equipment:
Nationally Recognized Testing Laboratories IE:
•
•
•
Underwriters Laboratories (UL)
Applied Research Laboratories Inc. (ARL)
Factory Mutual Research Corporation (FMRC)
www.safetyworksmaine.com
1910.303(a) Approval
All electrical conductors and equipment shall be
approved.
UNDERWRITERS
LABORATORIES
LISTED
ENCLOSED SWITCH
Issue AK 3225
1910.303(a)
NEC Article 110-2
5
6
www.safetyworksmaine.com
Basic Electrical 1910. 303
Examination, installation, and use of
equipment
b) Examination - Electrical equipment shall be
free from recognized hazards that are likely
to cause death or serious physical harm to
employees
-Suitability for installation for the purpose
intended.
www.safetyworksmaine.com
Basic Electrical 1910. 303
b) Examination continued.
•
•
•
•
•
•
Mechanical strength
Electrical insulation
Heating effects
Arcing effects
Classification by type , size, voltage, current
and specific use
Other factors which contributing to the
practical safeguarding of employees
www.safetyworksmaine.com
Basic Electrical 1910. 303
Installation and use Cont..
c) Electrical connections EI: Splices
d) Arcing parts shall be enclosed
B-40274-855
e) Marking
DANGER
HAZARD OF ELECTRICAL SHOCK
OR BURN. SEE INSTRUCTIONS
INSIDE DOOR
B-40274-855
f)
Identification of disconnecting means
www.safetyworksmaine.com
Basic Electrical 1910. 303
Design safety standards for electrical
systems.
g) 600 Volts or less
Working clearances (3 feet or greater) See
table S-1.
(2) Guarding of live parts greater than 50
volts by:
* Approved cabinets
* Room or vault
* Partitions or locations
* Elevations
of 8 feet or more
www.safetyworksmaine.com
Basic Electrical 1910. 303
(h) 600 Volts or More clearances (Greater
than 3 feet) (See table S-2 for Voltage
greater than 2500.)
(2) Guarding of live parts by
enclosures:
* Approved 7 foot fence area
* Room or vault with lock & key
* Accessible to qualified personnel only
www.safetyworksmaine.com
Basic Electrical 1910. 304
Wiring design and protection
Use and identification of grounded and
grounding conductors.
1. Identification of grounded and
grounding conductors
2. Polarity of connections
3. Use of grounding terminals and devices
www.safetyworksmaine.com
Normal Wiring
1910.304(a)(2)
Reverse Polarity
Hot
Neutral
Hot
Neutral
Ground
Ground
1910.304(a)(2)
NEC Article 200-11
www.safetyworksmaine.com
Basic Electrical 1910. 304
Wiring design and protection
(b) Branch circuits
1. Identification of Multi-wire circuits
2. Receptacles and cord connectors
3. GFCI protection
(c) Outside conductors 600 volts or less
2. Clearances of open conductors
* 10 feet - above sidewalks
* 12 feet - subjected to traffic
* 15 feet - Truck traffic
www.safetyworksmaine.com
Basic Electrical 1910. 304
Wiring design and protection
(e) Services
1. Disconnecting means
2. Services over 600 volts
* Guarding to allow
qualified
only
* High voltage signs
posted
www.safetyworksmaine.com
Basic Electrical 1910. 304
Wiring design and protection
f) Overcurrent protection
1. 600 volts or less
* Protection of conductors & equipment
* Continuity of grounded conductors
2. Over 600 volts
* Short circuit protection
www.safetyworksmaine.com
Basic Electrical 1910. 304
Wiring design and protection
g) Grounding
1. Systems to be grounded
* All 3 wire DC systems neutral conductor
* 2 wire DC systems
* AC circuits of less than 50 volts if……..
* AC systems of 50-1000 volts
2. Conductors to be grounded
* For AC premises wiring the identified
conductor shall be grounded
www.safetyworksmaine.com
Basic Electrical 1910. 304
Wiring design and protection
g) Grounding Cont..
3. Portable and Vehicle mounted generators.
4. Grounding connections
* For a grounded system, a grounding
electrode conductor shall be used to connect
both the equipment grounded conductor and the
grounded circuit conductor to the grounded
electrode
www.safetyworksmaine.com
Basic Electrical 1910. 304
Wiring design and protection
g) Grounding Cont..
5. Grounding path:
* The path to ground from circuits,
equipment, and enclosures shall be
permanent and continuous.
www.safetyworksmaine.com
1910.305
• Wiring Methods, components and
equipment for general use.
www.safetyworksmaine.com
1910.305(a)(2)(ii)(I) Flexible cords and
cables shall be protected from damage. Sharp
corners and projections shall be avoided. Flexible
cords and cables may pass through doorways or
other pinch points, if protection is provided to
avoid damage.
www.safetyworksmaine.com
1910.305(b)Cabinets, boxes,
and fittings.
(b)(1) Conductors entering
boxes, cabinets, or fittings.
Conductors entering boxes,
cabinets, or fittings shall be
protected from abrasion, and
openings through which
conductors enter shall be
effectively closed.
– Unused openings in cabinets,
boxes, and fittings shall also
be effectively closed.
www.safetyworksmaine.com
1910.305(c) Switches
1.Knife switches
shall be
connected so the
blades are dead
when the switch
is in the open
position
www.safetyworksmaine.com
1910.305(d) Switchboards and
Panelboards
• Switchboards located in
dry areas and accessible
to qualified personnel
only
• Panelboards shall be
mounted in cabinets and
have a dead front with
no exposed live parts
www.safetyworksmaine.com
1910.305(e) Enclosures for damp
or wet locations
• Cabinets, cutouts
boxes, fittings, and
panelboards shall be
weatherproof
• Switches, circuit
breakers, and
switchboards shall be
in weather proof
enclosures
www.safetyworksmaine.com
1910.305(f) Conductors for
general wiring
• All conductors shall
be insulated and
approved for the
voltage and
temperature and
distinguishable by
color
www.safetyworksmaine.com
1910.305(g) Flexible cords and
cables
• Shall be approved and
suitable for use and
conditions
• Shall be used for wiring of
fixtures, portable lamps,
appliances, pendants, etc
• Shall Not be used as a
substitute for fixed
wiring
www.safetyworksmaine.com
1910.305(h) Portable cables
over 600 volts
• Multi-conductor portable cable
shall be No. 14 or larger
• Connectors must be the locking
type
• Strain relief shall be provided
• If spliced, shall be of the
permanent molded, vulcanized
type
• High voltage hazard warnings
• Authorized and qualified
personnel only allowed in
enclosures
www.safetyworksmaine.com
1910.305(i) Fixture wires
• Shall be approved for the
voltage, temperature and
location
• Are permitted for use in
enclosed lighting fixtures
not subjected to bending
or twisting
• Are used for connecting
lighting fixtures to the
branch- circuit
www.safetyworksmaine.com
1910.305(j) Equipment for general
use
• Lighting fixtures, lampholders,
lamps and receptacles shall
have no live parts exposed
• Portable handlamps shall have
a substantial bulb guard and if
used in wet locations shall be
approved as such
• Receptacles and cord
connectors shall be compatible
for the voltage rating
• Receptacles installed in wet or
damp locations shall be
approved for use
www.safetyworksmaine.com
NFPA 70E
Most frequent cited by OSHA
•
•
•
•
•
•
•
1910.132(d) Hazard assessment
1910.332(a) Training
1910.333(a) Safety related work practices
1910.333(c)(2) Working on energized equipment
1910.334(c)(3) Rating of equipment
1910.335(a) Arc Flash PPE requirements
1910.335(b)(1) Labeling
www.safetyworksmaine.com
General Arc
Flash
warning for
employees.
Arc Flash warning
for employees
who work on
electrical panels and
systems.
www.safetyworksmaine.com
Arc Flash
What is Arc Flash?
The radiant energy and blinding light
created by an electric arc passing
through air between conductors. Arc
temperature can reach 35,000°F,
burning skin and igniting clothing at a
distance.
www.safetyworksmaine.com
Arc Flash
• What Causes Arc Flash?
• Just coming close to a high-amp source with a conductive
object can cause the electricity to flash over.
• Dropping a tool or otherwise creating a spark can ignite an
arc flash.
• Equipment failure due to use of substandard parts, improper
installation, or even normal wear and tear.
• Breaks or gaps in insulation.
• Dust, corrosion or other impurities on the surface of the
conductor.
www.safetyworksmaine.com
Arc Blast
High-energy arcing fault can produce a
considerable pressure wave and sound
blast. The intense heat from arc causes
the sudden expansion of air, resulting in
a blast. A 10,000 A arc at 480 volts is
equivalent to 800 MW or approximately
8 stick of dynamite.
www.safetyworksmaine.com
Arc blast can cause the following
injuries:
• Loss of memory or brain function from
concussion.
• Hearing loss from ruptured eardrums (sound
associated with blast can exceed 160
dB. Sound of jet engine only 145 db)
• Shrapnel wounds from metal parts
• Other physical injuries from being blown off
ladders, into walls, etc.
• A 40 Cal. blast will kill a person.
www.safetyworksmaine.com
Electrical PPE
www.safetyworksmaine.com